The invention relates to a magnetic bearing system provided with electromagnetic means arranged to hold a stationary part, as for example a stator, and a movable part, as for example a rotor, at a distance from each other during operation of the bearing by electromagnetic action, so that the movable part or rotor is movably supported, or rotatable, in relation to the stationary part or stator. The invention relates likewise to a servo system wherein the electromagnetic means are a component part, arranged so as to regulate the electromagnetic action whereby the stationary part or stator and the movable part or rotor are held at a distance from each other such that the clearance between the stationary part or stator and the movable part or rotor remains substantially constant.
The invention thus relates both to bearing systems permitting a rotary motion (rotation) and to bearing systems permitting a displacement (translation). In the following, for the sake of simplicity, the expressions stator and rotor will generally be used, without thereby implying that the embodiments referred to are limited thereto as other types of movable and stationary parts are within the scope of the invention.
Magnetic bearing systems in which there is no mechanical contact between stator and rotor have been developed in the field of space technology. In order to keep the clearance between the stator and rotor substantially constant during operation of the bearing, use is made of electromagnetic sensors that are able to transform variations occurring in the radial distance between the rotor and stator during operation into a corresponding electric control error signal. The control signal permits the electromagnetic means holding the rotor and the stator at a distance from each other by electromagnetic action to be adjusted so that the variation in radial distance is counteracted and a substantially constant air gap can be maintained.
Although such known magnetic bearings provide important technical advantages and possess high service dependability and long service life, the use of electromagnetic sensors is altered by engineering difficulties, while the regulating action is also subject to certain limitations.
An object of the invention is to eliminate the above stated disadvantages inherent in the prior art, while retaining the favorable technical properties and advantages of such prior art devices. In this way it is intended to enhance the versatility of such bearing systems.